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Castor oil works through its active compound, ricinoleic acid, which is released by intestinal lipases after ingestion. Ricinoleic acid activates prostaglandin EP3 and EP4 receptors in intestinal smooth muscle, stimulating fluid secretion and increasing peristalsis. This dual action softens stool and promotes bowel evacuation. The laxative effect typically occurs within 2-6 hours after oral administration. Evidence level: C (pharmacological studies and traditional use).
Does castor oil interact with any medications?
Castor oil may reduce absorption of oral medications due to accelerated intestinal transit time. This includes potential interactions with oral contraceptives, anticoagulants like warfarin, diuretics, and heart medications. Chronic use can deplete electrolytes, particularly potassium, which may compound effects of certain drugs. Patients taking regular medications should consult a healthcare provider before using castor oil. Allow 2-3 hours between taking medications and castor oil. Evidence level: C.
What is the correct dosage of castor oil for constipation?
The typical adult dosage for constipation is 15-60 ml (1-4 tablespoons) of castor oil taken orally as a single dose. It should be taken on an empty stomach for optimal effect, with results expected within 2-6 hours. Start with the lower dose (15 ml) to assess tolerance, as higher doses increase risk of cramping. Do not use for more than 7 consecutive days without medical supervision. Evidence level: C/Traditional.
Is castor oil safe to use during pregnancy?
Castor oil is unsafe during pregnancy when taken orally. It stimulates uterine contractions and has been used traditionally to induce labor, but this carries significant risks including fetal distress, meconium-stained amniotic fluid, and maternal dehydration from severe diarrhea. Pregnant women should avoid oral castor oil entirely. Topical application for skin or hair is generally considered acceptable during pregnancy, but consult a healthcare provider first. Evidence level: C.
Are castor seeds poisonous to humans?
Yes, raw castor seeds are highly poisonous. They contain ricin, one of the most toxic naturally occurring compounds known. Ingesting just 1-10 seeds can be fatal for adults; fewer seeds may kill children. Ricin poisoning causes severe gastrointestinal distress, dehydration, seizures, and potentially multi-organ failure. Never consume whole or chewed castor seeds. Commercial castor oil is safe because ricin is removed during processing. Evidence level: A (well-documented toxicology).
PubMed-compiled information sheet
This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.
Compiled from 29 PubMed articles · model: gemma4:31b
Summary
Ricinus communis, the castor oil plant, is a traditional medicinal plant containing both valuable phytochemicals and the highly potent toxin ricin [PMID:28722977, PMID:31892170].
Background
Ricinus communis L., commonly known as the castor oil plant, is a tropical and sub-tropical oil crop [PMID:28722977, PMID:29133924]. It is used globally for industrial purposes, such as biodiesel production, and as a traditional medicine [PMID:28973755, PMID:28722977].
Traditional uses
The plant has a history of thousands of years in traditional medicine for treating liver infections, stomach ache, flatulence, constipation, inflammation, warts, colic, enteritis, fever, and headache, and is used as a counter irritant [PMID:28722977]. It has also been recommended as an anthelmintic, antibacterial, laxative, and abortifacient, and for the treatment of wounds and ulcers [PMID:31174319].
Active compounds
Key compounds include ricin (a carbohydrate-binding protein/lectin found in seeds) [PMID:14579548, PMID:29133924], ricinoleic acid (an unusual fatty acid comprising approximately 90% of the seed oil) [PMID:10335384, PMID:29133924], and leaf constituents such as rutin, lupeol, and ricinine [PMID:35865958, PMID:37401758].
Mechanism of action
Ricin binds to cell surface carbohydrates and is internalized, where it causes cell death by inhibiting protein synthesis [PMID:14579548, PMID:31642648]. Rutin-rich leaf extracts may ameliorate muscle atrophy and oxidative stress via Nrf2 signaling [PMID:35865958].
Clinical evidence
Evidence DDexamethasone-induced muscle atrophy
Rutin-rich Ricinus communis leaf extract prevented loss of muscle function and mass and reduced mitochondrial oxidative damage in mice and C2C12 cells [PMID:35865958]
Ricin is a potent toxin; lethal doses in humans are estimated at 5-10 micrograms/kg via inhalation or injection [PMID:14579548, PMID:28722977]. Toxicity manifests as inflammation, gastrointestinal hemorrhages, renal tubular necrosis, hypoglycemia, fluid and protein loss, bleeding, and edema [PMID:14579548, PMID:31642648]. Ingestion of seeds can cause repeated vomiting, diarrhea, and transiently elevated serum creatinine [PMID:3964368].
Evidence summary
Evidence is primarily based on toxicological reviews and in vitro/animal studies. There is strong evidence regarding the toxicity of ricin, but clinical evidence for therapeutic use of leaf extracts is limited to preclinical models.
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